Function xsub_encode

libavcodec/xsubenc.c:114–202

}

static int xsub_encode(AVCodecContext *avctx, unsigned char *buf,
                       int bufsize, const AVSubtitle *h)
{
    uint64_t startTime = h->pts / 1000; // FIXME: need better solution...
    uint64_t endTime = startTime + h->end_display_time - h->start_display_time;
    int start_tc[4], end_tc[4];
    uint8_t *hdr = buf + 27; // Point behind the timestamp
    uint8_t *rlelenptr;
    uint16_t width, height;
    int i;
    PutBitContext pb;

    if (bufsize < 27 + 7*2 + 4*3) {
        av_log(avctx, AV_LOG_ERROR, "Buffer too small for XSUB header.\n");
        return AVERROR_BUFFER_TOO_SMALL;
    }

    // TODO: support multiple rects
    if (h->num_rects != 1)
        av_log(avctx, AV_LOG_WARNING, "Only single rects supported (%d in subtitle.)\n", h->num_rects);

    // TODO: render text-based subtitles into bitmaps
    if (!h->rects[0]->data[0] || !h->rects[0]->data[1]) {
        av_log(avctx, AV_LOG_WARNING, "No subtitle bitmap available.\n");
        return AVERROR(EINVAL);
    }

    // TODO: color reduction, similar to dvdsub encoder
    if (h->rects[0]->nb_colors > 4)
        av_log(avctx, AV_LOG_WARNING, "No more than 4 subtitle colors supported (%d found.)\n", h->rects[0]->nb_colors);

    // TODO: Palette swapping if color zero is not transparent
    if (((uint32_t *)h->rects[0]->data[1])[0] & 0xff000000)
        av_log(avctx, AV_LOG_WARNING, "Color index 0 is not transparent. Transparency will be messed up.\n");

    if (make_tc(startTime, start_tc) || make_tc(endTime, end_tc)) {
        av_log(avctx, AV_LOG_WARNING, "Time code >= 100 hours.\n");
        return AVERROR(EINVAL);
    }

    snprintf(buf, 28,
        "[%02d:%02d:%02d.%03d-%02d:%02d:%02d.%03d]",
        start_tc[3], start_tc[2], start_tc[1], start_tc[0],
        end_tc[3],   end_tc[2],   end_tc[1],   end_tc[0]);

    // Width and height must probably be multiples of 2.
    // 2 pixels required on either side of subtitle.
    // Possibly due to limitations of hardware renderers.
    // TODO: check if the bitmap is already padded
    width  = FFALIGN(h->rects[0]->w, 2) + PADDING * 2;
    height = FFALIGN(h->rects[0]->h, 2);

    bytestream_put_le16(&hdr, width);
    bytestream_put_le16(&hdr, height);
    bytestream_put_le16(&hdr, h->rects[0]->x);
    bytestream_put_le16(&hdr, h->rects[0]->y);
    bytestream_put_le16(&hdr, h->rects[0]->x + width -1);
    bytestream_put_le16(&hdr, h->rects[0]->y + height -1);